This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Since our laboratory's initial linkage of Type 2 diabetes to a mtDNA rearrangement in a three generation maternal pedigree 13 years ago, there has been increasing support for our hypothesis that mitochondrial dysfunction plays an important role in the etiology of Type 2 Diabetes Mellitus (DM) and the overlapping Metabolic Syndrome (MS). With this study we are planning to substantially expand upon the existing knowledge in the field by an extensive investigation of defects in mitochondrial oxidative phosphorylation (OXPHOS) caused potentially by deleterious sequence variants in the mitochondrial DNA (mtDNA). These diabetogenic mtDNA variants are proposed to range from recent, relatively severe, mutations resulting in substantial OXPHOS defects with familial DM &MS to ancient, relatively mild, polymorphisms that result in partial OXPHOS defects and an increase in the risk to develop DM &MS. To test this hypothesis, we propose to analyze the mtDNAs of an existing collection of samples from Taiwan Chinese families, which exhibit maternal transmission of DM &MS as well as approximately 500 Taiwan Chinese DM/MS non familial cases and controls to identify causal pathogenic mtDNA mutations. The study is designed to look for associations between the common Asian mtDNA lineages (haplogroups) and predisposition to MS and DM. The Taiwanese cohort of samples will not be included under this IRB application but will fall under a separate, exempt status application which has been submitted to the Investigational Review Board. (application submitted 11/01/05).